Type I error rates for moderated multiple regression analysis

Abstract

The method of moderated multiple regression is increasingly being applied in the search for moderator variables in industrial and organizational psychology. Because of frequent failures of the method in revealing moderator effects in empirical studies—in which such effects are strongly expected—it has been suggested that the procedure may lack statistical power with respect to hypothesis tests about moderating effects and, therefore, is inappropriate for the purposes of conventional moderator analyses. We evaluated this conclusion with computer simulation data. Our study indicated that the method is not overly conservative and that the Type I error rate of moderated multiple regression is approximately .05 at α = .05. Moreover, a proposed alternative multivariate procedure, principal component regression, is shown to have a Type I error rate that approaches unity under ordinary conditions when applied to the evaluation of moderator effects. (PsycInfo Database Record (c) 2025 APA, all rights reserved)